Red Flag Threat IndexA Means to Quantify/Assess

Greg Murdoch, Sr. Forecaster, IMET Chris Gitro (BGM) and Ryan Barnes Weather Forecast Office, Midland, TX

Midland

Red Flag Threat Index

Another idea focused around a numerical relationship between wind and RH Wind/RH =20/15=1.3

Other ratios give same result

30/23=1.3

Interesting - more applicable to a sliding RF scale

Bismark NWS

Thought about how indices are used/developed in severe weather i.e., Supercell Parameters, etc

Composite indices that represent likelihood of certain traits or characteristics of storms, these are good, but too complicated

Red Flag Threat Index

Started looking at other more easily understood indices

K-INDEX K = (T850 - T500) + Td850 - (T700 - Td700)

SHOWALTER INDEX SI = T500 - Tp500

TOTAL TOTALS INDEX TT = T850 + Td850 - 2T500

Started to see a pattern with these indices

Reminds of how another index is calculated

Stability Moisture Haines Index = (Tp1-Tp2) + (Tp1-Ttd1) = A + B

Red Flag Threat Index

Term A - RH Term B - 20ft Wind Speed 10-15% =1 20-22 mph=1 5-9% =2 23-27 mph=2 <= 4% =3 >=28 mph=3 RFTI = A + B

Unit-less number ranging from 2 to 6

RFTI Steeped heavily in Climatology

Ranges for terms A and Bbased on a set RAWS datafrom MAFs local RF climo(18k RF obs) from whichpercentile rankings wheredeveloped

6.68%8.42%

14.51%

31.97%

20.29%

8.15%0.32%0.05%0.29%

1.42% 2.20%

5.68%

Dec 1985 - Apr 2008 Fire WXPercent of Fire WX Obs Per Month

All Stations

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Percentile Rankings - Good fit

• Fire Management community uses percentile rankings – A means to Quantify data

Term A - RH Term B - 20ft WS 10-15% =1 20-22mph=1 5-9% =2 23-27mph =2 <= 4% =3 >=28mph =3

Final Product in MAFs GFE

Term A - RH

RFTI

Term B - WS 1 Indicates that only one element of a Red Flag has been met Documented problematic fires that occur outside of RF conditions for west Texas Plains (Lindley, et al)

0 Indicates neither RH or WS terms are within Red Flag

Other considerations

• All Red Flag days are not equal• Dependent on magnitude of specific weather elements • Antecedent fuel conditions• Response to RFW may be different depending on Planning

Level or on local decision makers• During drought periods may not take “as much weather” to produce control problems (if fuels predisposed)

• RFTI quantifies severity of Red Flag conditions and increases SA

• RFTI not a predictor of fire starts, utilized in analysis, forecast, Fire Potential(?)

More considerations

• Created in the grids for Fire Weather Zones/CWFA/PSA, falls out of grids

• Similarly to RH/Wind/Temp grids RFTI can be calculated hourly on GFE

• A max for the day

• Takes a little heavy lifting up front to get the climo data set up

• Quickly see where worst conditions are

• By quantifying RF conditions forecasters can include enhanced wording in products or briefings

Red Flag Threat Index

Severe Fire Weather Analysis - Apr 9 2009 Outbreak

Severe Fire Weather Analysis

Went back and calculated RFTI

Plotted RFTI/10hr FSM from RAWS

3 distinct areas (solid red) where RFTI 5 or > and 2-3% 10hr FSM “Marry-Up”

13-16 CDT 9 Apr 2009 RFTI – Red 5 10hr FSM dashed 2-3%

RFTIFSM

When combined with other data

13 CDT 9 Apr 2009Temperature Departure

Conventional data… Dry slot

Mid level speed max

Thermal Ridge

Including:

Temperature Departure

Overlay not a surprise to see a favored area

Null case for W TX

Feb 25 2008 Outbreak

Fires over a large portion of Texas, as were positive temperature departuresRFTI 3 or greater over a large part of the state, RFTI max along temperature departureThis case really started to bring to light that RFTI is a composite index - RH, wind, TCombination of RFTI and temperature departure caught the largest fires, Glass/Silver

5-2, 4-3, 3-3

Jan 1 2006 Outbreak

Fire occurrence map shows that fires occurred over a large part of TXTemperature Departure map shows large positive temperature departure over stateRFTI and 10hr FSM also depicts a large area of concernRFTI must still be used with other data, i.e., CFWP thermal ridge

5-5, 4-5

SummaryWe are learning more about fire weather forecasting for the plains

Developing conceptual models of how to better forecast fire weather

Intensity - Duration - Aerial Coverage Principles

Fire Weather Forecasting similar approach to forecasting storms Downscale and utilize

Severe Fire Weather AnalysisRecognize large scale patterns

Summary Continued On Regional Outbreaks days multiple ingredients of Critical Fire Weather Patterns come together

Thermal Ridge Mid level Wind Speed Maxima (Jet) Dry slotPositive T Departure Chinook/Downslope Winds Dryline

Tools like the RFTI can help quantify/assess the conditions • Just how bad will the weather get• Still each case is a little different, thermal ridge orientation, fuel• Indices are empirical and need other data, temperature and fuel• ***RFTI thought of as Composite Index***

• RH and Wind• Catches thermal ridge because temperature is built into RH

Part 2 – Decision SupportHistorically NWS Meteorologist issue products for specific groups, aviation and fire weather, do TX WFOs really know how the products are used?

Room to gain better understanding of user objectives, i.e., TFS Fire Management

• Assessing Fire Potential - Occurrence and Response Capability

Fire Weather Watches are of utmost importance to plan effectively

How large is TFS response area?Gives coordination a new perspective, where are worst expected?Be aware of concerns outside of WFO boundaries

How much time does TFS have to prepare?Lead time is critical, time to move resources to most

strategic locationEquipment maintenance issues, how long to get it fixed

Moving forward to aid in Fire Operations Decision Support Recent Advances

WFOs can generate GFDI, RFTI, and Temperature Departure maps

Generated at the click of a button or automatically

GFDIT DepartureRFTI

Overlay EraImproving our overlay capabilities we can get better idea of where different weather features align with each other and with fuelsAvailability of climate data - directly improves fire weather forecastBy use of the GFDI Midland can get fuel data into GFE, through a curing factor

RFTIGFDI

RFTITemperature Departure

The Future• Midland believes this to be the beginning of a paradigm shift

and a partial glimpse of future Fire Weather Forecasting

• By incorporating: Climatology through percentile ranks in RFTI Fuels through use of the GFDI Climatology in temperature departure

analysis

• Get a more complete picture of fire weather and fuels, provides greater awareness and good decisions

Red Flag

RFTI

GFDI

Midland

Current 1400 1300

Y Y N

6 5 1

65 45 35

Ultimate GoalTactical/Strategic Decision Support Tools for Fire Operations

Tactical Decision Support Tool – Matrix example

Statewide – PSA Based Strategic Decision Support Tool

Y Y N

4 2 0

45 35 15

Red Flag

RFTI

GFDI

Today Day 2 Day 3

Trans Pecos Matrix

PSA/WFO Matrix Page

Y Y N

6 5 1

65 55 30

Y Y N

3 5 0

45 55 10

Y Y N

5 2 1

50 40 25

Y Y N

2 5 0

40 45 10

Red Flag

RFTI

GFDI

Red Flag

RFTI

GFDI

Trans Pecos Rolling Plains

North TexasSouth Plains

Today Day 2 Day 3 Today Day 2 Day 3

Today Day 2 Day 3 Today Day 2 Day 3

Temperature Departure

RFTI GFDI

Assimilating this data into Decision Support we begin our move to the next level of Science and Service